<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        function test(a, b) {
            console.log(b)
            b = 6
            console.log(b)
            function b() { }
            console.log(b)
        }
        test()
    </script>
</body>

</html>